If continuous paper webs pasted together as mentioned above takes a final form in which the continuous paper webs which are printed and processed in given sizes in a direction of their travel are cut in a fixed size, modes such as tension of each continuous paper web traveling through a processing unit need to be kept constant always at a given site. And, during the time period in which the processing unit starts to operate, the continuous paper web which has traveled until the mode becomes constant comes to be a loss. For this reason, the time period (distance of paper travel) until the mode of a continuous paper web becomes constant is desirably as short as possible.
Until a mode such as the tension of a continuous paper web traveling along a line of travel having a processing unit comes to be maintained always constant at a given site, namely until it arrives at a constant equilibrium state thereof, the continuous paper web needs to be driven to travel over a certain time period depending on an amount of delivery of the continuous paper web from its supply section, a peripheral speed thereof on a feed roll at a given site in the travel path, a slip factor of the traveling continuous paper web with a surface of the roll and a property of the continuous paper web on its expansion and contraction.
And, in the state that continuous paper webs prior to pasting are driven to travel to a pasting unit as they remain unstable in their tension, the continuous paper webs as their traveling itself is unstable tend to cause such as meandering thereof and it takes a considerable time until the state is reached that the continuous paper webs are each driven to travel stably. As a consequence, an increased amount of paper loss occurs that largely exceeds the range of a simple multiple corresponding to the number of continuous paper webs compared with a general apparatus in which a continuous paper web delivered from a single paper roll is processed.
Designed to solve these problems, a working apparatus has been known in which after two continuous paper webs, upper and lower, are pasted together, a pattern that matches a pattern previously printed on the lower continuous paper is printed on the upper continuous paper web so that the pattern of the two continuous paper webs are matched without need to later register them between the continuous paper webs (see, e.g., JP 2003-95237 A).
In this prior art apparatus in which one (upper) continuous paper web is printed after it is pasted on the other continuous paper web, if it is desired that the one continuous paper web be one with a multicolored pattern a plurality of printing units for multicolored printing must be arranged in the apparatus, giving rise to a problem that the entire apparatus becomes large-sized in the direction in which paper webs travel.
Also, in such a working apparatus, if the one continuous paper web is one with a single-colored pattern all printing units other than the one in operation must stand idle, causing a problem that an operation becomes wasteful of equipment.
With the foregoing problems taken into account, it is an object of the present invention to provide a working apparatus for pasting two continuous paper webs together, each having a pattern, which without the need to be equipped with a printing unit downstream of the pasting unit can be made small-sized as a whole and permits the two continuous paper webs when pasted to be registered in pattern with reduced paper loss.